| 摘要 |
PURPOSE:To avoid a decline of a tightening force in a cryogenic condition by a method wherein a length of a tightening rod suitable for tightening coils, which are contracted in the cryogenic condition, to their axial direction is memorized by a shape memory alloy. CONSTITUTION:Screws 11 made of a shape memory alloy are attached between end plates 3 put on both ends of a magnet proper 10 and tightened by nuts 12. When the superconductive magnet 10 is cooled to a cryogenic temperature, the screws 11 are curved by a reversible shape memory effect and a contraction rate between two end plates 3 to the axial direction is the same as, or larger than, the thermal contraction rate to the axial direction of a whole laminated coil. Therefore, a tightening force of the screws 11 at a cryogenic temperature is the same as, or larger than, the tightening force at a room temperature and each coil 1 and each spacer 2 are tightened by the two end plates 3 and a play along the axial direction is avoided. |
